Device and method for the amelioration of ectatic and irregular corneal disorders

Abstract

Devices and methods for the amelioration of ectatic corneal disorders using corneal augmentations derived from corneal tissue are disclosed. The shape of the augmentation is determined using data obtained from mapping of a patient's cornea based on computerized corneal topography and tomography. Factors considered include the maximum keratometry and specific iso-deviation contours. In one embodiment, an augmentation is a corneal inlay, intended for insertion into an intrastromal pocket. In a further embodiment, the augmentation is a corneal onlay, intended to be positioned over a region of the cornea from which the epithelial layer has been removed. The corneal onlay is held in place until the epithelial layer regrows over the augmentation. In a further embodiment, the inlay or onlay augmentation is followed by a post-augmentation, further reshaping of the corneal augmentation. In one embodiment, this further reshaping is photorefractive keratectomy (PRK) surgery.

1 - 21 . (canceled) 
     
     
         22 . A method for amelioration of an abnormality of a cornea, the method comprising:
 determining a severity of the abnormality of the cornea;   creating a corneal map of the cornea quantifying a deviation of the abnormality from an optimal corneal shape;   calculating, using the corneal map and the severity, a three-dimensional shape of a corneal augmentation to ameliorate the abnormality of the cornea;   producing the corneal augmentation with the three-dimensional shape; and   augmenting the cornea with the corneal augmentation.   
     
     
         23 . The method of  claim 22 , wherein producing the corneal augmentation comprises obtaining a corneal template from a source other than the cornea being treated, wherein the corneal template is one of a corneal autograft, corneal allograft, a corneal xenograft, and a manufactured corneal tissue. 
     
     
         24 . The method of  claim 22 , wherein the abnormality is keratoconus, the severity is measured by a maximum keratometry (K-max), and the corneal map is obtained using corneal tomography or corneal topography. 
     
     
         25 . The method of  claim 24 , wherein a maximum thickness of the corneal augmentation is proportional to the maximum keratometry of the keratoconus and is determined by the equation: t=10×K-max−300, where t represents the maximum thickness in μm, and K-max represents the maximum keratometry measured in diopters. 
     
     
         26 . The method of  claim 22 , wherein the three-dimensional shape is a sector cut from a doughnut shape. 
     
     
         27 . The method of  claim 26 , wherein the sector cut from the doughnut shape has an inner radius of about 3 mm to about 5 mm and an outer radius of about 7 mm to about 9 mm. 
     
     
         28 . The method of  claim 27 , wherein the sector cut from the doughnut shape has a uniform thickness determined using the equation: t=10×K-max−300, where t is thickness in μm, and K-max is maximum keratometry measured in diopters. 
     
     
         29 . The method of  claim 22 , wherein the corneal map is an elevation map and the three-dimensional shape has a plan projection that is one of a curve, a polygon, a lenticule, a doughnut, a crescent or an arc. 
     
     
         30 . The method of  claim 29 , wherein the plan projection is at least in part a best fit to an iso-elevation line of the elevation map. 
     
     
         31 . The method of  claim 22 , wherein producing the three-dimensional shape comprises generating, using a processor, a cutting file based on the corneal map and the severity, wherein the cutting file contains instructions to form the corneal augmentation using a femtosecond laser. 
     
     
         32 . The method of  claim 22 , wherein the corneal augmentation is an inlay and augmenting the cornea further comprises creating an intra-stromal cavity using a femtosecond laser, wherein the intra-stromal cavity is sized and shaped to accommodate the inlay. 
     
     
         33 . The method of  claim 22 , wherein the corneal augmentation is an onlay placed external to the cornea being treated and augmenting the cornea further comprises removing, using a femtosecond laser, a contiguous region of epithelial tissue corresponding in area to a plan projection of the corneal augmentation. 
     
     
         34 . The method of  claim 33 , wherein augmenting the cornea further comprises retaining the onlay on the cornea using a surface chamfer of epithelial tissue on a periphery of the removed contiguous region of epithelial region. 
     
     
         35 . The method of  claim 22 , the method further comprising after augmentation, reshaping the cornea with photorefractive keratectomy (PRK) surgery using an excimer laser. 
     
     
         36 . A device for amelioration of an abnormality of a cornea, the device comprising:
 a corneal augmentation having a three-dimensional shape,   wherein the three-dimensional shape has a plan projection that is one of a curve, a polygon, a lenticule, a doughnut, a crescent, or an arc, and   wherein the plan projection is at least in part a best fit to an iso-elevation line of an elevation map.   
     
     
         37 . The device of  claim 36 , wherein the three-dimensional shape is a sector cut from a doughnut shape having an inner radius of about 3 mm to about 5 mm and an outer radius of about 7 mm to about 9 mm. 
     
     
         38 . The device of  claim 37 , wherein the three-dimensional shape has a uniform thickness determined using the equation: t=10×K-max−300, where t is thickness in μm, and K-max is maximum keratometry measured in diopters. 
     
     
         39 . The device of  claim 36 , wherein the three-dimensional shape is determined by a method comprising:
 determining a measure of severity of the abnormality of the cornea;   creating a corneal map of the cornea quantifying a deviation of the abnormality from an optimal corneal shape; and   calculating, using the corneal map and the measure of severity, the three-dimensional shape of the corneal augmentation to ameliorate the abnormality of the cornea.   
     
     
         40 . A system for amelioration of an abnormality of a cornea, the system comprising:
 at least one processor configured to:
 generate a corneal map of a patient indicating a measure of severity of the abnormality and a deviation between the abnormality and an optimal corneal shape; 
 calculate, using the corneal map, a three-dimensional shape of a corneal augmentation to ameliorate the abnormality of the cornea; and 
 cause a laser and a moveable stage to produce the corneal augmentation having the three-dimensional shape. 
   
     
     
         41 . The system of  claim 40 , wherein the corneal map is an elevation map and the three-dimensional shape has a plan projection that is one of a curve, a polygon, a lenticule, a doughnut, a crescent or an arc, and wherein the plan projection is at least in part a best fit to an iso-elevation line of the elevation map.